A glucose-derepressed promoter for expression of heterologous products in the filamentous fungus Aspergillus nidulans

We describe a putative binding sequence (GCGGGGC) for the glucose-responsive represser protein CreA at two positions upstream of the transcription start site of the alcohol dehydrogenase I ( alc A) gene of Aspergillus nidulans . To positively identify the putative binding sites as CreA-specifie, the GCGGGGC blocks were mutated at five internal nucleotide positions to GTACTAC and reintroduced into the wild type alc A promoter driving expression of the endogenous alcohol dehydrogenase I gene. This CreA-binding site variant was then transformed into an AlcR constitutive A. nidulans host strain (T2625) and growth was monitored in the presence of the non-metabolized glucose analogue, 2-deoxyglucose. Positive transformants were selected by their ability to grow using ethanol as a carbon source hi the presence of 2-deoxyglucose. Similar CreA binding site variant alc A promoters should permit the alc A-driven expression of heterologous genes in A. nidulans in the presence of glucose, the preferred carbon source for biomass accumulation and provides a model for controlling carbon-catabolite regulated expression in other expression systems.